Metaphor Design Considerations

Metaphors are very good at conveying a great deal of new information quickly. In order for them to function effectively, several things must be true:

• The hearer must have a sufficient understanding of the vehicle. By sufficient, we mean that they must be aware of all of the features and attributes of the vehicle that are required and relevant to the topic.
  • For example, in our earlier example about John the pig, it is essential that the hearer know what a pig is. In addition, they must also know about the relevant attributes of a pig, namely, that they are messy. Failure to meet either of those conditions will result in a failed metaphor. Additionally, a more thorough understanding of the attributes and reputation of a pig will result in a richer, fuller, more complex metaphor.
    
• There must also be good functional congruence between the vehicle and the topic. By this we mean that the ways and means in which the vehicle functions (i.e., all of its attributes and behaviors etc.) must be functionally similar to the topic.
  • For example, children are often disorganized and messy, leaving toys and dirty clothes all around. Accordingly, we could say that. We could say that John is a child, since both child and pig share this attribute. But if our intention is say only that John is messy with his desk and to imply he is not admired, and not that he is immature and playful, saying he is a child would convey inaccuracies about John. Another, perhaps more relevant example is used often in teaching about electricity. Electricity and water are often metaphorically linked in teaching about circuits. The idea is that electricity flows like water through a circuit: open a gate or create a pathway and the water will go through it. Unfortunately, water has properties which do not hold true for electricity. Water will continue to flow even if it hits a block, simply pooling up behind the obstruction until it spills over and creates a new path. Circuits, on the other hand, rely on being able to block and unblock electricity without any leakage. Further, a circuit is by definition, circular (hence the name) and must return to its origin to be complete. These, along with other dissimilarities, make this metaphor a poor one, because although it conveys a lot of information quickly, much of it is inaccurate and will result in conceptual errors which can actually interfere with later learning.

     This is related to another design consideration: overextension. Even when both the topic and vehicle share similar attributes, allowing for effective metaphor design, the designer must be aware that learners do not automatically apply ONLY the relevant/intended attributes of the vehicle to the topic, but will instead attempt to bring all attributes to bear. The designer should ask themselves how far the connection between the topic and vehicle can be extended before it breaks down and/or begins to convey inaccurate/unintended information. The further the metaphor can be extended, the more powerful it is. Of course, it can be difficult to find truly powerful metaphors, and there is probably no metaphor which does not break down at some point. It is more practical to search for metaphors which are powerful enough to convey the intended information, to identify where and when they are likely to break down, and to draw attention to any flaws or incongruencies between the topic and vehicle. In other words, let the learners know where and when to stop applying vehicle attributes to the topic.

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